Internal Medicine

A $32$-year-old woman, gravida 2, para 1, at $16$ weeks gestation presents to the emergency department reporting profound and rapidly worsening muscle weakness. Over the past $48$ hours, she has found it increasingly difficult to climb stairs and this morning was unable to stand up from a seated position. Her medical history is notable for bilateral parotid gland enlargement and a chronic "gritty" sensation in her eyes, for which she frequently uses over-the-counter artificial tears. She also reports a history of multiple dental cavities despite good oral hygiene. Vital signs are within normal limits. Physical examination reveals flaccid paralysis of the proximal lower extremities with absent deep tendon reflexes. Sensory examination is normal. Laboratory findings show:

* Serum sodium: $140 \text{ mEq/L}$
* Serum potassium: $1.8 \text{ mEq/L}$
* Serum chloride: $118 \text{ mEq/L}$
* Serum bicarbonate: $12 \text{ mEq/L}$
* Blood urea nitrogen: $14 \text{ mg/dL}$
* Serum creatinine: $0.8 \text{ mg/dL}$
* Urine pH: $6.8$

Which of the following is the most likely mechanism responsible for this patient's acute presentation?

A 38-year-old woman is referred to the nephrology clinic for evaluation of a persistent acid-base abnormality. Over the past 6 months, she has experienced progressive fatigue, generalized muscle weakness, and one episode of passing a small, radiopaque kidney stone. Her medical history is significant for severe dental caries and bilateral parotid gland enlargement, which has been present for 3 years. She complains of a constant sensation of "sand in her eyes." She takes no medications.

Vital signs are within normal limits. Physical examination shows dry mucous membranes and mildly swollen, non-tender parotid glands. Motor strength is 4/5 in the proximal lower extremities.

Laboratory studies:
$Na^+$: $140\text{ mEq/L}$
$K^+$: $2.6\text{ mEq/L}$
$Cl^-$: $115\text{ mEq/L}$
$HCO_3^-$: $12\text{ mEq/L}$
Blood urea nitrogen: $14\text{ mg/dL}$
Serum creatinine: $0.9\text{ mg/dL}$

Urinalysis:
pH: $6.5$
Specific gravity: $1.012$
Protein: Negative
Blood: Negative
Glucose: Negative
Ketones: Negative

Which of the following findings is most likely to be present in this patient?

A physician is evaluating an adult patient with newly diagnosed, severe, and resistant hypertension. The physician considers various secondary causes based on the patient's history and subtle physical exam clues. Match each suspected secondary cause of hypertension with its most appropriate initial screening test.

A 48-year-old man is brought to the emergency department by his wife due to a severe headache, fever, and confusion that began 24 hours ago. His temperature is 39.1°C (102.4°F), blood pressure is 142/86 mmHg, pulse is 110/min, and respirations are 18/min. Physical examination reveals nuchal rigidity. Neurologic examination shows a new-onset right-sided facial droop and right upper extremity weakness. Suspecting acute bacterial meningitis, the physician prepares to initiate the management workup. Arrange the following steps in the most appropriate chronological order of execution.

Match the following clinical etiologies with their classic presentation on a serum electrolyte panel.

A 24-year-old woman with type 1 diabetes mellitus is brought to the emergency department due to a 2-day history of severe nausea, vomiting, and abdominal pain. She has not taken her insulin because she was unable to keep food down. Her blood pressure is $90/60\text{ mmHg}$, pulse is $125/\text{min}$, and respirations are $28/\text{min}$ and deep. Laboratory results show:

Serum glucose: $580\text{ mg/dL}$
Serum sodium: $132\text{ mEq/L}$
Serum potassium: $3.0\text{ mEq/L}$
Serum chloride: $98\text{ mEq/L}$
Serum bicarbonate: $10\text{ mEq/L}$
Arterial blood gas pH: $7.15$
Urine ketones: positive (+++)

Arrange the following management steps in the most appropriate chronological sequence for this patient.

Match each clinical presentation describing a patient with renal dysfunction to the most characteristic urinalysis sediment finding associated with their underlying pathology.

Match each of the following clinical laboratory profiles to its most likely underlying pathophysiologic diagnosis. Assume the following reference ranges for all profiles:

A 48-year-old woman is brought to the emergency department by her husband due to progressive confusion, ataxia, and slurred speech that began earlier today. Her husband reports that she was feeling entirely well until this morning. Last night, they attended a celebratory dinner where she consumed a large meal consisting heavily of pasta and bread, along with a single glass of wine. Later in the evening, she took two tablets of acetaminophen for a mild headache.

Her past medical history is significant for Crohn disease, which necessitated an extensive small bowel resection two years ago. She currently takes a multivitamin but no other daily medications.

On physical examination, her temperature is $37.0^\circ\text{C}$ ($98.6^\circ\text{F}$), blood pressure is $118/76$ mm Hg, pulse is $88$/min, and respiratory rate is $22$/min. She is disoriented to time and place. Neurologic examination reveals a broad-based gait and slurred speech, but no focal motor or sensory deficits.

Laboratory results are as follows:

Urine toxicology screen is negative.

Which of the following best explains the pathogenesis of this patient's current acid-base disturbance?

An emergency department evaluation is requested for a $34$-year-old woman due to continuous gingival bleeding, recurrent epistaxis, and extensive bruising that began two days ago. She has felt profoundly fatigued for the last week. Vital signs include a temperature of $37.4^{\circ}\text{C}$ ($99.3^{\circ}\text{F}$), blood pressure of $110/70\text{ mmHg}$, heart rate of $105/\text{min}$, and respiratory rate of $18/\text{min}$. Examination shows diffuse petechiae on both lower extremities and active mucosal oozing in the oropharynx.

Laboratory results are as follows:

A review of the peripheral blood smear reveals an abundance of atypical promyelocytes, many of which contain bundles of needle-like intracytoplasmic inclusions.

Arrange the following evaluation and management steps in the most appropriate chronological sequence for this patient.

A 62-year-old woman is evaluated in the intensive care unit on hospital day 6 for persistent altered mental status. She was initially admitted for septic shock secondary to a perforated diverticulum, which required emergency bowel resection and broad-spectrum antibiotics. She was extubated yesterday, and her hemodynamics are currently stable off vasopressors. However, she remains severely lethargic and unresponsive to verbal commands. Her temperature is $36.2^\circ\text{C}$ ($97.2^\circ\text{F}$), blood pressure is $112/68\text{ mmHg}$, pulse is $64\text{/min}$, and respiratory rate is $14\text{/min}$. Physical examination reveals a somnolent patient who withdraws all extremities to pain. There is no palpable thyromegaly, and deep tendon reflexes exhibit a delayed relaxation phase. Due to her lethargy, a thyroid panel is obtained, which reveals the following results:

Thyroid-stimulating hormone (TSH): $0.2\ \mu\text{U/mL}$ (Reference: $0.4-4.0\ \mu\text{U/mL}$)
Free thyroxine (T4): $0.6\ \text{ng/dL}$ (Reference: $0.9-1.7\ \text{ng/dL}$)
Total triiodothyronine (T3): $45\ \text{ng/dL}$ (Reference: $80-200\ \text{ng/dL}$)

Which of the following is the most appropriate management regarding her thyroid laboratory findings?

A $28$-year-old woman is evaluated in the clinic for profound fatigue, cold intolerance, and inability to produce breast milk. Her symptoms began shortly after she delivered a healthy infant three months ago. Her medical records indicate that the delivery was complicated by a severe hemorrhage requiring massive volume resuscitation and transfusion of four units of packed red blood cells. She has not had a menstrual period since the delivery. Her temperature is $35.9^\circ\text{C}$ ($96.6^\circ\text{F}$), blood pressure is $90/60\text{ mm Hg}$, and pulse is $60\text{/min}$.

Laboratory results show:
Thyroid-stimulating hormone (TSH): $0.2\text{ \mu U/mL}$ (Normal: $0.4-4.0\text{ \mu U/mL}$)
Free T4: $0.4\text{ ng/dL}$ (Normal: $0.9-1.7\text{ ng/dL}$)

Which of the following is the most likely diagnosis?

An 82-year-old woman residing in a skilled nursing facility is brought to the outpatient clinic by her daughter for a routine follow-up visit. The daughter reports that over the past $3$ days, the patient's urine has appeared unusually cloudy and has a strong, foul odor. The patient has a medical history of Alzheimer dementia, hypertension, and osteoarthritis. She does not report any pain, and the daughter has not noticed any changes in her mother's baseline mental status, oral intake, or behavioral patterns. Vital signs are temperature $37.1^\circ\text{C}$ ($98.8^\circ\text{F}$), pulse $76$/min, blood pressure $130/75$ mm Hg, and respirations $14$/min. Physical examination reveals a pleasant woman who is oriented to person only, which is at her baseline. The abdomen is soft and non-tender. There is no suprapubic or costovertebral angle tenderness. A clean-catch urine sample is obtained, and urinalysis shows:

pH: 7.0
Specific gravity: 1.015
Leukocyte esterase: positive
Nitrites: positive
WBC: 45/hpf
RBC: 2/hpf
Bacteria: numerous

Which of the following is the most appropriate next step in management?

Emergency medical personnel transport a 72-year-old woman to the hospital after she experienced a witnessed generalized tonic-clonic seizure at her home. Her husband states that she was recently prescribed hydrochlorothiazide for essential hypertension and has been constantly drinking water due to a severe dry mouth.

Upon triage evaluation, the patient is stuporous and withdraws from painful stimuli but does not open her eyes. Her mucous membranes are moist. Vital signs demonstrate a blood pressure of $142/88 \text{ mm Hg}$ and a heart rate of $84/\text{min}$. A rapid metabolic panel reveals a critically low serum sodium concentration of $111 \text{ mEq/L}$ with a serum osmolality of $232 \text{ mOsm/kg}$. The critical care team initiates an algorithmic protocol to stabilize her condition and manage her electrolytes.

Arrange the following management steps in the most appropriate chronological sequence for this patient.

A 26-year-old woman is evaluated on the medical ward on hospital day $3$. She was initially admitted for severe right-sided flank pain, nausea, vomiting, and a temperature of $39.2^\circ\text{C}$ ($102.6^\circ\text{F}$). On admission, urinalysis revealed marked pyuria and bacteriuria, and she was started on empiric intravenous ceftriaxone for acute pyelonephritis.

Today, she reports significant improvement in her symptoms and is tolerating a regular diet. Her temperature is $37.0^\circ\text{C}$ ($98.6^\circ\text{F}$), blood pressure is $118/76\text{ mmHg}$, and pulse is $78\text{/min}$. Physical examination shows resolution of the right costovertebral angle tenderness. Blood cultures drawn on admission show no growth. The urine culture from admission grew $>100,000\text{ CFU/mL}$ of *Escherichia coli*. The isolate susceptibility report is as follows:

Which of the following is the most appropriate next step in management?

A 42-year-old woman presents to the clinic complaining of severe, generalized muscle weakness that began earlier today. She reports that she has felt increasingly fatigued over the last several months. Her past medical history is significant for recurrent kidney stones and a diagnosis of Sjögren syndrome. She currently takes no medications. Vital signs are within normal limits, except for a respiratory rate of $20/\text{min}$. Physical examination reveals dry mucous membranes and marked proximal muscle weakness in the bilateral lower and upper extremities.

Laboratory studies are obtained:

Serum chemistry:
Sodium: $140 \text{ mEq/L}$
Potassium: $2.1 \text{ mEq/L}$
Chloride: $114 \text{ mEq/L}$
Bicarbonate: $14 \text{ mEq/L}$
Blood urea nitrogen: $14 \text{ mg/dL}$
Creatinine: $0.9 \text{ mg/dL}$

Arterial blood gas (room air):
pH: $7.26$
PaCO $_2$: $29 \text{ mmHg}$
PaO $_2$: $98 \text{ mmHg}$

Urinalysis:
pH: $6.8$
Specific gravity: $1.012$
Protein: Negative
Glucose: Negative

Which of the following is the most likely primary mechanism responsible for this patient's clinical and laboratory findings?

A $41$-year-old woman is brought to the emergency department by her husband due to progressive weakness, easy bruising, and persistent bleeding from her gums for the past $48$ hours. Her temperature is $37.6^\circ\text{C}$ ($99.7^\circ\text{F}$), blood pressure is $110/70\text{ mmHg}$, and heart rate is $108\text{/min}$. Physical examination reveals widespread petechiae and purpura over her extremities.

Laboratory studies show:
- Hemoglobin: $7.8\text{ g/dL}$
- Leukocyte count: $4,500\text{/mm}^3$ (with $60\%$ atypical promyelocytes)
- Platelet count: $18,000\text{/mm}^3$
- Prothrombin time: $22\text{ sec}$ (prolonged)
- Activated partial thromboplastin time: $54\text{ sec}$ (prolonged)
- Fibrinogen: $60\text{ mg/dL}$ (decreased)
- D-dimer: $>10,000\text{ ng/mL}$ (markedly elevated)

A peripheral blood smear demonstrates large, abnormal myeloid cells with prominent primary granules and multiple rod-like cytoplasmic inclusions.

Arrange the following steps in the most appropriate chronological order for the diagnosis and management of this patient.

Match each clinical presentation of community-acquired pneumonia (CAP) with the most appropriate empiric antimicrobial regimen based on current clinical guidelines.

A 42-year-old man is brought to the emergency department by his partner due to profound weakness and lethargy. For the past four days, he has experienced profuse, watery diarrhea with up to 10 large bowel movements daily. He has not been able to tolerate oral intake. His temperature is $37.2^\circ\text{C}$ ($99.0^\circ\text{F}$), pulse is $112/\text{min}$, respirations are $22/\text{min}$, and blood pressure is $98/64\text{ mm Hg}$. Physical examination reveals dry mucous membranes, flat neck veins, and decreased skin turgor. Neurologic examination shows generalized muscle weakness with strength rated $3/5$ in both upper and lower extremities. Laboratory studies show the following:

Based on the laboratory findings, which of the following is the most accurate characterization of this patient's acid-base status?

Match each clinical vignette describing a patient with a renal disorder to the most characteristic histopathologic or immunofluorescent finding expected on their renal biopsy.